Loops vs Resend: which one should send your product's email?

What the money buys

The two numbers are not like for like, and most comparison pages gloss over that. Resend's plans are measured in emails: $20 covers 50,000 of them whether they go to 500 people or 50,000. Loops measures subscribed contacts and then includes unlimited sends to them, together with the editor, workflows and transactional sending to people outside your audience. So one app that mails each of 10,000 users four times a month sends 40,000 emails. That fits inside Resend's $20 Pro plan, against $99 at Loops, but the Loops figure also covers the lifecycle tooling you would otherwise build or buy.

Scale the same app to 50,000 subscribers and 200,000 emails a month. 200,000 emails is a stop on Resend's volume slider, where Scale read $160 on October 7, 2026 (Pro tops out at $35 for 100,000 on that slider, so Scale is the plan at this size). Loops shows $249. The gap narrows because Resend charges for volume while Loops charges for audience size. If your users get one email a month, Resend gets cheaper still; if they get twenty, Loops' unlimited sends become the better deal.

The first integration, side by side

Loops is event-driven. Your app tells it that something happened, and a workflow built in the Loops editor decides which emails follow. This is the documented call to send an event, from the Loops API reference:

curl --request POST \
  --url https://app.loops.so/api/v1/events/send \
  --header 'Authorization: Bearer <token>' \
  --header 'Content-Type: application/json' \
  --data '
{
  "email": "alex@company.com",
  "userId": "usr_7f8e9d0c1b2a",
  "eventName": "signup",
  "eventProperties": {
    "plan": "pro"
  }
}
'

Resend's most direct path is sending a message from code. This is the Node example from the Send Email reference with the idempotency option described on its idempotency keys page:

import { Resend } from 'resend';

const resend = new Resend('re_xxxxxxxxx');

await resend.emails.send(
  {
    from: 'Acme <onboarding@resend.dev>',
    to: ['delivered@resend.dev'],
    subject: 'hello world',
    html: '<p>it works!</p>',
  },
  {
    idempotencyKey: 'welcome-user/123456789',
  },
);

The idempotency key matters because queues retry. Resend checks whether it has already sent an email with the same key in the last 24 hours, so a retried request does not mail the customer twice. The key is carried in an Idempotency-Key HTTP header, and the SDK exposes it as an option, as above. That is a point for Resend if your own code does the sending. With Loops you send an event rather than an email, so duplicate protection comes from how you design the workflow and its entry conditions.

Transactional email on each

Both do it. Loops lets you build a transactional email in its editor, publish it, and call the transactional endpoint with the email address, a transactional ID and your data variables. The call can add the recipient to your audience with addToAudience, and the docs say transactional email goes to any address, whether or not it is in your audience. Its pricing page states that transactional sending is included at no additional charge on paid plans. Resend's transactional path is its core product: send from code, or define a Template once and reuse it.

If your templates come from a builder or framework, note one real difference. Loops lets you bring your own MJML in place of its editor and use data variables inside it, and its docs name Figma plugins that export for it. If you write templates in MJML or React Email, check which tool takes your output without conversion. Resend is made by the team behind React Email, which is the natural fit if your templates are React components.

Lifecycle automation

This is where the products used to be easy to separate, and now they overlap. Resend's documentation describes Automations: a series of steps triggered by custom events from your application, which you can build in the dashboard or through an API, with a run history for debugging. Loops builds its product around workflows, events and audience segments, so that is where its editor and tooling are deepest. If your sequences are short (a welcome email, a nudge after three days), either works. If you need many branches, goals and segments maintained by marketing, Loops is closer to that job.

Choose Loops if…

• A product marketer or founder, not an engineer, will write and change onboarding and retention emails.
• You want sending, workflows and transactional email under one invoice with no per-seat fees.
• Your audience is under 1,000 contacts and you want a free plan that includes every feature, accepting the Loops footer.

Choose Resend if…

• Developers own the email code and want a plain API, idempotency keys and React-based templates.
• Most of your volume is transactional, and a per-email price beats a per-subscriber one.
• You prefer to keep lifecycle logic in your own application, or your sequences are short enough for Automations.

Switching later

The sending domain is the easy part: verify DNS records for the new provider before you move traffic, and keep the old one running during the overlap. The hard part is the automation logic, because event names and workflow conditions do not export. Write down each sequence's trigger, delay, exit condition and suppression rule before you leave, then rebuild one low-risk flow first. For the broader picture of how marketing and transactional streams differ, read transactional vs marketing email, and for other developer-first senders compare Resend vs Postmark and email for transactional use.